267 research outputs found
Application of a portable FTIR for measuring on-road emissions
The objective of this work was the development of an onroad
in-vehicle emissions measurement technique
utilizing a relatively new, commercial, portable Fourier
Transform Infra-Red (FTIR) Spectrometer capable of
identifying and measuring (at approximately 3 second
intervals) up to 51 different compounds. The FTIR was
installed in a medium class EURO1 spark ignition
passenger vehicle in order to measure on-road
emissions. The vehicle was also instrumented to allow
the logging of engine speed, road speed, global position,
throttle position, air-fuel ratio, air flow and fuel flow in
addition to engine, exhaust and catalyst temperatures.
This instrumentation allowed the calculation of massbased
emissions from the volume-based concentrations
measured by the FTIR. To validate the FTIR data, the
instrument was used to measure emissions from an
engine subjected to a real-world drive cycle using an AC
dynamometer. Standard analyzers were operated
simultaneously for comparison with the FTIR and the
standard analyzer results showed that most pollutants
(NOx, CO2, CO) were within ~10% of a standard analyzer
during steady state conditions and within 20% during
transients. The exception to this was total HC which was
generally 50% or less than actual total HC, but this was
due to the limited number of hydrocarbons measured by
the FTIR. In addition to the regulated emissions, five
toxic hydrocarbon species were analyzed and found to
be sensitive to cold starts in varying proportions. Finally,
FTIR data was compared to results from a commercially
available on-road measurement system (Horiba OBS-
1000), and there was good agreement
Heterogeneously entrapped, vapor-rich melt inclusions record pre eruptive magmatic volatile contents
Rediseño de la intranet de la empresa Controltek S.A.C. usando servidores redundantes open source sobre vlan´s para optimizar el flujo de información
La empresa de la cual será objeto de estudio tiene problemas frecuentes desde hace
algunos años con su Intranet, lo cual genera problemas de conexión internas en la red de
la empresa, perdida de información, caídas repentinas de los servidores y virus
informáticos que llegan desde el exterior de la Intranet.
La presente tesis se focaliza en el objetivo de proponer un rediseño de la Intranet con el
cual se podrá mejorar el rendimiento de la red para optimizar el flujo de información y
minimizar los agentes infecciosos para la empresa, con el único propósito de que todos
los trabajadores puedan estar conectados a la red sin interrupciones y poder acrecentar la
productividad. Esta propuesta de mejora se da utilizando los Simuladores Riverbed
Modeler Academic Edition y Packet Tracer, en donde se puede diseñar la actual topología
de red Star con muchos dominios de broadcast y rediseñar la nueva topología de red con
VLAN´s limitando estos dominios. Estos diseños realizados nos llevan a poder confrontar
las dos Topologías, apreciando las deficiencias en la red actual y las mejoras en el nuevo
rediseño planteado.
Se utiliza también los programas XAMPP y Workbench para elaborar la base de datos con
el Modelo Relacional y por último Linux para llevar a cabo los servidores redundantes;
Todo eso para alcanzar los objetivos propuestos.
Este rediseño planteado permite organizar y gestionar mejor la red, garantizando el ancho
de banda, prioridad de la transmisión y fragmentando el dominio de broadcast al utilizar
switches; obteniendo un progreso significativo en el rendimiento de la red, permitiendo
una fácil y fluida circulación de información para cada uno de los trabajadores que son
parte de en las áreas o departamentos de la empresa y a los eslabones que constituyen la
pirámide jerárquica de la administración. Eso sí, con apego a las mejores especificaciones
técnicas y a la mejor visión futurista que en el momento sea posible.
Palabras clave: red, switch, router, VLAN, broadcast, ancho de banda, latencia, base de
datos.Tesi
Draft Genome Sequence of Pseudoalteromonas sp. Strain JC3
We report the draft genome sequence for Pseudoalteromonas sp. strain JC3, an isolate obtained from an aquaculture facility for whiteleg shrimp (Litopenaeus vannamei). The JC3 genome suggests multiple mechanisms for microbial interactions, including a type VI secretion system and potential for antibiotic production
Stability and Change in Self-Reported Sexual Orientation Identity in Young People: Application of Mobility Metrics
This study investigated stability and change in self-reported sexual orientation identity over time in youth. We describe gender- and age-related changes in sexual orientation identity from early adolescence through emerging adulthood in 13,840 youth ages 12–25 employing mobility measure M, a measure we modified from its original application for econometrics. Using prospective data from a large, ongoing cohort of U.S. adolescents, we examined mobility in sexual orientation identity in youth with up to four waves of data. Ten percent of males and 20% of females at some point described themselves as a sexual minority, while 2% of both males and females reported ever being “unsure” of their orientation. Two novel findings emerged regarding gender and mobility: (1) Although mobility scores were quite low for the full cohort, females reported significantly higher mobility than did males. (2) As expected, for sexual minorities, mobility scores were appreciably higher than for the full cohort; however, the gender difference appeared to be eliminated, indicating that changing reported sexual orientation identity throughout adolescence occurred at a similar rate in female and male sexual minorities. In addition, we found that, of those who described themselves as “unsure” of their orientation identity at any point, 66% identified as completely heterosexual at other reports and never went on to describe themselves as a sexual minority. Age was positively associated with endorsing a sexual-minority orientation identity. We discuss substantive and methodological implications of our findings for understanding development of sexual orientation identity in young people
Natural and synthetic tetracycline-inducible promoters for use in the antibiotic-producing bacteria Streptomyces
Bacteria in the genus Streptomyces are major producers of antibiotics and other pharmacologically active compounds. Genetic and physiological manipulations of these bacteria are important for new drug discovery and production development. An essential part of any ‘genetic toolkit’ is the availability of regulatable promoters. We have adapted the tetracycline (Tc) repressor/operator (TetR/tetO) regulatable system from transposon Tn10 for use in Streptomyces. The synthetic Tc controllable promoter (tcp), tcp830, was active in a wide range of Streptomyces species, and varying levels of induction were observed after the addition of 1–100 ng/ml of anhydrotetracycline (aTc). Streptomyces coelicolor contained an innate Tc-controllable promoter regulated by a TetR homologue (SCO0253). Both natural and synthetic promoters were active and inducible throughout growth. Using the luxAB genes expressing luciferase as a reporter system, we showed that induction factors of up to 270 could be obtained for tcp830. The effect of inducers on the growth of S.coelicolor was determined; addition of aTc at concentrations where induction is optimal, i.e. 0.1–1 μg/ml, ranged from no effect on growth rate to a small increase in the lag period compared with cultures with no inducer
Natural and synthetic tetracycline-inducible promoters for use in the antibiotic-producing bacteria Streptomyces
[EN] Bacteria in the genus Streptomyces are major producers of antibiotics and other pharmacologically active compounds. Genetic and physiological manipulations of these bacteria are important for new drug discovery and production development. An essential part of any ‘genetic toolkit’ is the availability of regulatable promoters. We have adapted the tetracycline (Tc) repressor/operator (TetR/ tetO ) regulatable system from transposon Tn 10 for use in Streptomyces . The synthetic Tc controllable promoter (tcp), tcp830 , was active in a wide range of Streptomyces species, and varying levels of induction were observed after the addition of 1–100 ng/ml of anhydrotetracycline (aTc). Streptomyces coelicolor contained an innate Tc-controllable promoter regulated by a TetR homologue (SCO0253). Both natural and synthetic promoters were active and inducible throughout growth. Using the luxAB genes expressing luciferase as a reporter system, we showed that induction factors of up to 270 could be obtained for tcp830 . The effect of inducers on the growth of S.coelicolor was determined; addition of aTc at concentrations where induction is optimal, i.e. 0.1–1 μg/ml, ranged from no effect on growth rate to a small increase in the lag period compared with cultures with no inducerSIThe authors acknowledge gifts of plasmids and strains from Prof. Leadlay, Prof. Hillen, Prof. Bujard, Dr Herron and Dr Paget. The authors thank Dr Sumby, Dr Ding and Wael Hussein for the construction of several plasmids and vectors. The authors also thank Prof. Williams for the use of Lucy. This work was funded by the BBSRC. Funding to pay the Open Access publication charges for this article was provided by JIS
Repeated Changes in Reported Sexual Orientation Identity Linked to Substance Use Behaviors in Youth
Purpose—Previous studies have found that sexual minority (e.g., lesbian, gay, bisexual) adolescents are at higher risk of substance use than heterosexuals, but few have examined how changes in sexual orientation over time may relate to substance use. We examined the associations between change in sexual orientation identity and marijuana use, tobacco use, and binge drinking in U.S. youth.
Methods—Prospective data from 10,515 U.S. youth ages 12-27 years in a longitudinal cohort study were analyzed using sexual orientation identity mobility measure M (frequency of change from 0 [no change] to 1 [change at every wave]) in up to five waves of data. Generalized estimating equations were used to estimate substance use risk ratios and 95% confidence intervals; interactions by sex and age group were assessed.
Results—All substance use behaviors varied significantly by sexual orientation. Sexual minorities were at higher risk for all outcomes, excluding binge drinking in males, and mobility score was positively associated with substance use in most cases (p\u3c.05). The association between mobility and substance use remained significant after adjusting for current sexual orientation and varied by sex and age for selected substance use behaviors. This association had a higher positive magnitude in females than males and in adolescents than young adults.
Conclusions—In both clinical and research settings it is important to assess history of sexual orientation changes. Changes in reported sexual orientation over time may be as important as current sexual orientation for understanding adolescent substance use risk
Modeling policy development: examining national governance of stem cell-based embryo models
Researchers can now coax human pluripotent stem cells to imitate the structure and spontaneous self-organization of the developing human embryo. Although these stem cell-based embryo models present an advantageous alternative to embryo research, they also raise ethical and policy challenges. In 2021, the International Society for Stem Cell Research revised its Guidelines for Stem Cell Research and Clinical Translation, providing contemporaneous best practices for ethical conduct in the field. The Guidelines complement national governance frameworks; however, they also contain contentious and aspirational norms that might catalyze change in research practice and in the enactment of national policies. Using a sample of 11 research-intensive countries, the authors compare research policy frameworks against the International Society for Stem Cell Research Guidelines to showcase how developments in global and national policies might affect stem cell-based embryo model research governance and illustrate fertile areas for ethical reflection and policy development
Mending the gaps: ethically sensitive cells and the evolution of European stem cell policy
The past decades witnessed the slow evolution of Europe's heterogeneous stem cell (SC) policy and substantial scientific advances in the field. Parallel to these developments, professional organizations have grown in influence. With the recently revised International Society for Stem Cell Research's Guidelines as a backdrop, we address the evolution of SC policies in 46 European countries and discuss how they fare against evolving ethical standards, societal views, and scientific advances. We identify areas of convergence, divergence, and the suitability of extant governance mechanisms to meet their stewardship roles. Europe represents a rich case study as it encompasses a wide range of policy approaches present worldwide. Comparative studies provide an opportunity to promote insight into national frameworks and to foster international harmonization
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